Ultrastructural observation of Pneumocystis carinii in bronchoalveolar lavage fluid from non-AIDS patients with P carinii pneumonia.

Abstract

To investigate the morphology of Pneumocystis carinii in vivo, we studied the ultrastructure of P carinii in bronchoalveolar lavage fluid (BALF) obtained from four non-AIDS patients with P carinii pneumonia (PCP), and observed the morphologic changes after treatment in one patient. Every form recognized in the normal life cycle of P carinii, ie, thick-walled cysts, crescent-shaped cysts, and trophozoites, was detected in the pretreatment BALF specimens. In the posttreatment BALF, P carinii revealed marked ultrastructural changes such as the elongation of thick-walled cysts, the degeneration of intracystic bodies, and the disappearance of trophozoites. Massive debris derived from P carinii was still found in the BALF even after the treatment. Examination of P carinii in BALF, including ultrastructural observations, might help us to evaluate the disease status and the effect of treatment in patients with PCP.